When the inhibitor closely resembles the substrate in its molecular structure and inhibits the activity of the enzyme, it is known as a competitive inhibitor and the process is called competitive inhibition. Due to its close structural similarity with the substrate, the inhibitor competes with the substrate for the substrate-binding site of the enzyme. Consequently, the substrate cannot bind and as a result, the enzyme action declines.
Eg:- Inhibition of succinic dehydrogenase by malonate which closely resembles the substrate succinate in structure.
